2001 5.3 Tapping Sound

Hello Everyone,

The wife pulls into the garage last night in my 2001 Z-71 and there is a loud tapping sound on the driver side towards the front of the engine.

For some background, over the last week, the oil pressure has been erratic. At first start, it only went up to about 40. Head down the street and at the first light, the pressure starts to slowly go down while waiting on the light. Hit zero psi once the other day and I put it into neutral and revved and the pressure came back up. Once the engine was warm, the pressure stayed between 40 & 60, and no sounds.

The tapping has me worried and wanted to run it by you guys for some thoughts. My first thought is a lifter. What do you think?

I also realize I need to change the oil pump. If it is a lifter, would getting the oil pressure back up pump up the lifter?

Engine has 200K and uses no oil. Always has run great, except for this recent issue.

Try Castrol high mileage oil the oil has something in it that stops tapping sounds it did when we had a older MPV that's what made me start using it instead of regular Castrol well my 5.7 doesn't make any tapping sounds I just said high mileage is well worth it.

The wife pulls into the garage last night in my 2001 Z-71 and there is a loud tapping sound on the driver side towards the front of the engine.

For some background, over the last week, the oil pressure has been erratic. At first start, it only went up to about 40. Head down the street and at the first light, the pressure starts to slowly go down while waiting on the light. Hit zero psi once the other day and I put it into neutral and revved and the pressure came back up. Once the engine was warm, the pressure stayed between 40 & 60, and no sounds.

The tapping has me worried and wanted to run it by you guys for some thoughts. My first thought is a lifter. What do you think?

I also realize I need to change the oil pump. If it is a lifter, would getting the oil pressure back up pump up the lifter?

Engine has 200K and uses no oil. Always has run great, except for this recent issue.

A tight engine can handle lower oil pressure. As things get worn and sloppy. (crank bearings and journals, as they wear they'll gobble up more and oil volume) you'll need a higher volume pump and heavier oil so it won't squeeze out under ignition. I'd knock a rod cap off and check the top bearing and see if she's been starving for oil, or evidence of low oil pressure. Check the bottom bearing for the mains, as the crank is always pushed down harder with more fuel/air.
200k I'd stuff in $75 bearings and an oil gasket regardless of lifter tick or not. Easier then swapping a crank that's got square journals.

most likely you have a rod starting to knock if you had zero oil pressure. i would recommend a full rebuild with 200k on the motor. if you put new bearings on a egg shaped crank journal your just throwing your time & money away. besides everything else has 200k whats going to break next?

Re: 2001 5.3 Tapping Sound

Originally Posted by daleTX

if you put new bearings on a egg shaped crank journal your just throwing your time & money away.

I've installed new bearings on cranks with alot of miles numerous times. Usually end up with 4x the oil pressure. 200k doesn't always mean the crank is out of round. I've gambled 0.0015 out of round on my vortec and she still tugs good after 60k. 20w50 year around. Can't say it'll work on this situation, or the next, but with my garbage worn out stuff, I don't care. I'm just suggesting a gamble.

And you can roll in new mains with the crank still in, I peen a roofing nail, make it flat/curved on the journal, and use the crank oil hole to roll out the old and roll in the new.

Make note they only roll out and back in of one direction.

And install a mechanical pressure gauge. Or at least temporary to get an accurate answer. Maybe tee off block and run side by side with the electronic one in cluster?